WO2016055318A1

WO2016055318A1 - Lighting device

Info

Publication number: WO2016055318A1
Application number: PCT/EP2015/072497
Authority: WO
Inventors: Gerard Kums; Boudewijn Ruben DE JONG; Hans Meijer; Antonius Adrianus Maria Marinus
Original assignee: Philips Lighting Holding B.V.
Priority date: 2014-10-06
Filing date: 2015-09-30
Publication date: 2016-04-14

Abstract

The present invention relates to a lighting device (10), comprising: a carrier (12) including a substrate (14) and electrical connection means; and light sources (28) mounted on a surface (34) of the carrier and connected to the electrical connection means, wherein the carrier is shaped with an outer perimeter (18) and structured by at least one void (30) going through the substrate of the carrier, and wherein the carrier is bent such that said surface on which the light sources are mounted forms a double curved surface. The present invention also relates to a method of manufacturing a lighting device, and a carrier for a lighting device.

Description

Lighting device

FIELD OF THE INVENTION

The present invention relates to a lighting device, for example a retrofit light emitting diode (LED) lamp. The present invention also relates to a method of manufacturing a lighting device. The present invention also relates to a carrier for a lighting device.

BACKGROUND OF THE INVENTION

US 7086756 discloses an LED light bulb comprising a housing with a base connected thereto. Light is provided by a plurality of light emitting elements that are connected to a formed substrate that contours to the form of the inside wall of the housing. The formed substrate is constructed of flexible material that generally has electrical connectors formed within its layered construction. The formed substrate is cut or pressed out from a substrate of circuit board material. The formed substrate is cut in such fashion that it is provided with a plurality of individual finger-like projections and each of which further carry light emitting elements thereon, in addition to standoffs. The formed substrate may be provided with perforations or score lines. However, each finger-like projection is a single curved surface, which limits the overall shape and light emission directions that the light bulb can have.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome or alleviate this problem, and to provide an improved lighting device.

According to a first aspect of the invention, this and other objects are achieved by a lighting device, comprising: a carrier including a substrate and electrical connection means; and light sources mounted on a surface of the carrier and connected to the electrical connection means, wherein the carrier is shaped with an outer perimeter and structured by at least one void going through the substrate of the carrier, and wherein the carrier is bent such that said surface on which the light sources are mounted forms a double curved surface.

"Double curved surface" may here be construed as the surface being bent around two axes, which may be non-parallel, or that it has two axes of rotation. The invention is based on the understanding that by shaping and structuring the carrier in a suitable way, the carrier may be bent to achieve a desired 3D shape, with no or minimal stress in the material of the carrier, even though the material(s) of the carrier per se may be relatively stiff. Also, the carrier may be bent after the light sources have been mounted to it, which means that the light sources can be mounted to the carrier in a flat state using conventional mounting techniques.

The carrier may include a central through-hole, wherein the outer perimeter of the carrier is curved. The carrier may for example have an overall "donut shape" (toroid).

The at least one void may include lines radially extending from a central region of the carrier towards the outer perimeter of the carrier. The lines may for example extend from the central through-hole of the carrier. The lines may for example be cut by a laser. The lines serve to increase extra degrees of freedom. It should be noted that

WO2014/087366 discloses a lamp with radially extending lines in a conducting layer, i.e. not in a substrate/carrier.

Preferably, the lines do not extend all the way to the outer perimeter of the carrier. They may for example only extend between 40-60% of the distance from the central through-hole to the outer perimeter of the carrier, in order not to compromise the integrity of the carrier.

The electrical connection means may include an electrically conducting layer provided over the substrate, wherein electrically conducting layer includes electrically insulating separations. The electrically conducting layer may also be thermally conducting, to give it heat spreading functionality. The electrically conducting layer may for example be made of metal, such as Cu.

The light sources may be positioned offset compared to said lines. In other words, the light sources are positioned not in line with the (cut) lines in the carrier. In this way, build-up of stress at the positions where the light sources are mounted to the carrier (typically by a solder joint) may be avoided when the carrier is bent. The light sources may for example be positioned on Z-shaped or U-shaped diversions of the electrically insulating separations, allowing heat spreading areas of the carrier between the electrically insulating separations to be maximized. Alternatively, the light sources may be positioned in line with said lines.

The lines may be aligned with the electrically insulating separations. In this way, the (cut) lines do not interfere with the electrical and heat spreading properties of the device. Said carrier may be a first carrier, wherein the lighting device further comprises a second carrier with light sources mounted thereon, and wherein the first and second carriers are arranged back to back with a heat resistant foam layer in between. The second carrier may be of the same type as the first carrier. The heat resistant foam layer is useful for heat dissipation, by ensuring a good thermal contact of the carrier with the cover member(s).

The lighting device may further comprise: a base for connection to lamp socket (e.g. an Edison base); a driver electrically connected to the light sources (e.g. for converting AC to DC); and at least one optically transmissive cover member covering the light sources. The cover member(s) may for example be transparent or translucent.

According to a second aspect of the invention, there is provided a method of manufacturing a lighting device, which method comprises: providing a flat carrier; mounting light sources on a surface of the flat carrier including a substrate and electrical connection means; wherein the carrier is shaped with an outer perimeter and structured by at least one void going through the substrate of the carrier, and wherein the method further comprises: bending the shaped and structured carrier such that said surface on which the light sources are mounted forms a double curved surface. This method may be referred to as "place flat first and 3D shape later". This aspect of the invention may exhibit the same or similar features and/or technical effects as the first aspect. By first providing a flat carrier and mounting the light sources while the carrier is still flat, the same techniques as used in traditional SMD board assembly can advantageously be used. Hence, there is no need of mounting the light sources on an already double curved surface. Note that the outer perimeter and/or at least one void can be provided before or after the light sources are mounted.

Bending the carrier may include sandwiching the carrier and optionally another such carrier between two 3D shaped cover members of the lighting device.

Alternatively, the carrier may be attached to a 3D shaped cover member of the lighting device, wherein another such carrier is attached to another 3D shaped cover member of the lighting device, and wherein the 3D shaped cover members then are assembled. The carrier(s) may be pre-bent before being arranged between the cover members, in order to facilitate the assembling.

According to a third aspect of the invention, there is provided a carrier for a lighting device, which carrier comprises: a substrate; electrical connection means; an outer perimeter; a central through hole; and lines going through the substrate of the carrier and radially extending from the central through hole towards the circular outer perimeter of the carrier. This aspect of the invention may exhibit the same or similar features and/or technical effects as the first and/or second aspect, and vice versa.

It is noted that the invention relates to all possible combinations of features recited in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.

Fig. 1 is a side view in slight perspective of a carrier with light sources for a lighting device according to an embodiment of the present invention.

Fig. la is a cross-sectional view along section A-B of fig. 1.

Fig. lb is a cross-sectional view along section C-D of fig. 1.

Fig. 2 is a side view a lighting device comprising the carrier of fig. 1.

Fig 2a is an exploded side view of dual carriers.

Fig. 3 is a partial side view of a carrier with light sources according to another embodiment of the present invention.

Fig. 4 is a partial side view of a carrier with light sources according to yet another embodiment of the present invention.

Fig. 5 is a side view of a carrier with light sources for a lighting device according to still another embodiment of the present invention.

Fig. 6 is flowchart of a method of manufacturing a lighting device according to an embodiment of the present invention.

Figs. 7a-7c are schematic side views of carriers according to further embodiments of the present invention.

As illustrated in the figures, the sizes of layers and regions may be exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

Fig. 1 shows a carrier 12 for a lighting device 10 according to an embodiment of the present invention. The carrier 12 in fig. 1 is shown in a flat state before it is assembled with the rest of the lighting device 10.

The carrier 12 includes a substrate 14 (see fig. la) and electrical connection means. The electrical connection means may for example include an electrically conductive layer 16 provided on one side of the substrate 14. The electrically conducting layer 16 may also be thermally conducting, to give it heat spreading functionality. The electrically conducting layer 16 may for example be made of Cu. The carrier 12 may for example be a printed circuit board (PCB), such as a polyimide flex circuit, a thin FR4 board, or a thin Al carrier with a printed polymeric conductor. A dielectric layer (not shown) may be provided between the substrate and the electrically conductive layer, in case the electrically conductive layer (conductor) is printed.

The carrier 12 further includes a curved outer perimeter 18. The outer perimeter 18 may for example be circular. The outer perimeter 18 may also be continuous. The carrier 12 also includes a central through-hole 20. The central through-hole extends from one side 22 of the carrier 12 to the opposite side of the carrier. The central through-hole 20 may also be circular, giving the carrier an overall "donut shape".

Furthermore, electrically insulating separations 24 are provided in the electrically conducting layer 16. The separations 24 may radiate as straight lines from the central through-hole 20 to the curved outer perimeter 18, whereby a plurality of sector- shaped areas or pads 26 are formed. The areas 26 between the separations 24 may serve as heat spreading areas. Furthermore, they allow serial connection of light sources 28, as will be explained further below.

The carrier 12 is further structured by a plurality of voids, namely cut lines 30. The lines 30 are continuous and straight. The lines 30 go through at least the substrate 14 of the carrier 10, see fig. lb. Furthermore, the lines 30 extend radially from the central through- hole 20 towards, but not all the way to, the outer perimeter 18. The lines 30 may for example extend between 40-60% of the distance from the central through-hole 20 to the outer perimeter 18 of the carrier 12, in order not to compromise the integrity of the carrier 12. The cut lines 30 may be aligned with the electrically insulating separations 24, as shown in fig. 1. The lines 30 may for example be cut by a laser. The structure defined by the central through- hole 20 and the cut lines 30 in the carrier 12 may be referred to as an "inverted hub-and- spoke structure".

One cut line 30' extends from the central through-hole 20 all the way to the outer perimeter 18. And each area 26' adjacent the cut line 30' is connected to an electrode 32. The insulating separations 24' next to the cut line 30'may have an offset extension compared to the straight line insulating separations 24, so that the distances between the light sources 28 becomes equal.

The light sources 28 are mounted on a surface 34 on one side 22 of the carrier 12. The light sources are arranged along the outer perimeter 18. Namely, the light sources 28 are mounted over the insulating separations 24,24' so that each light source 28 is connected to two adjacent areas 26,26'. In this way, a serial connection of the light sources 28 may be achieved. The light sources 28 may be soldered to the electrically conducting layer 16 of the carrier 12. The light sources 26 may be LEDs. However, other solid state light sources can be used as well, such as OLEDs, PLEDs or the like.

The opposite side of the carrier 12 may be embodied in the same way as the side 22 shown in fig. 1, with another conducting layer and another set of electrically insulating separations and light sources ("double side board"), as indicated with dashed lines in figures la and lb. Alternatively, the lighting device 10 may comprise two separate carriers 12 ("single side board") mounted back to back, with a heat resistant foam layer in between, see fig. 2a.

The carrier 12 is preferably thin, with an overall thickness of for example 85- 125 μιη, preferably 120 μιη. The substrate may for example have a thickness between 50- 90μιη, whereas the electrically conducting layer 16 may have a thickness of 35-70 μιη. Since the carrier 12 is structured by the cut lines 30 and has the "donut shape", the carrier 12 is flexible, even though the material(s) of the carrier 12 per se may be relatively stiff.

Fig. 2 is a side view of a lighting device 10 comprising the carrier 12 of fig. 1. The lighting device 10 may for example be a retrofit or replacement bulb for general lighting applications, such as conventional lighting fixtures or luminaires.

The lighting device 10 comprises a base 36 for mechanical and electrical connection to a lamp socket (not shown). The base 36 may for example be an Edison base provided with an external threading, but other type of lamp bases known to the skilled person could be used as well. Next to the base 36, the lighting device 10 comprises a cavity 38 in which a driver 40 is situated. The driver 40 is electrically connected to the light sources 28 via the electrodes 32 and the pads 26,26'. The driver 38 may for example be adapted to convert AC from the mains to DC for the light sources 28.

The carrier 12, when attached in the lighting device 10, is bent such that the surface 34 on which the light sources 28 are mounted form a double curved surface, as shown in fig. 2. In other words, the carrier 12 is curved (or twisted) out of its (original) plane. The double curved surface may for example resemble a double-helix. In other words, the carrier 12 is a double-helical shaped surface, positioned in parallel to the longitudinal axis of the lighting device 10. Preferably, the lighting device 10 comprises two separate carriers 12,12' mounted back to back, with a heat resistant foam layer 54 in between, as illustrated in fig. 2a. Fig. 2a shows the two carriers 12,12' in a flat or pre-bent state. The carriers 12,12' are enclosed and mechanically attached to the remaining lighting device 10 by means of two cover members 42a and 42b between which the carriers 12 are arranged. The foam layer 54 ensures that the electrically conducting layer 16 of carrier 12 is in good mechanical (and thermal) contact with the opposite cover member 42b. This good thermal contact is useful for the heat dissipation. The cover members 42a and 42b may for example be transparent or translucent. They can for example be made of plastics. The cover members 42a and 42b can be molded or printed to a 3D shape. The cover members 42a and 42b may also comprise lens sections 44 aligned with the light sources 28. The cover members 42a and 42b may also define the cavity 38 for the driver. Instead of two one-sided carriers, one two-sided carrier as discussed above could be included in the lighting device 10.

Upon operation of the lighting device 10, the light sources 28 emit light in various directions as defined by the double curved surface 34. The emitted light may be further manipulated by the lens sections 44. Heat generated by the light sources 28 is transferred into the carrier 12 at the areas 26,26'.

Fig. 3 is a partial side view of a carrier 12 with light sources 28 according to another embodiment of the present invention. The carrier of fig. 3 is similar to the carrier of fig. 1, except that the light sources 28 are positioned offset compared to the cut lines 30. In this way, build-up of stress at the positions where the light sources 28 are mounted to the carrier 12 may be avoided when the carrier 12 is bent. In fig. 3, the light sources 28 are positioned on Z-shaped diversions 46 of the electrically insulating separations 24. In yet another embodiment shown in fig. 4, the light sources 28 are positioned on U-shaped diversions 48 of the electrically insulating separations 24. The Z- or U-shaped diversions 46,48 allow the heat spreading areas 26 of the carrier 12 to be maximized. The carriers of figures 3 and 4 may be used in the lighting device 10 shown in fig. 2. Fig. 5 is a carrier 12 with light sources 28 for a lighting device according to still another embodiment of the present invention. The carrier of fig. 5 is similar to the carrier of fig. 1, except that the central through-hole 20', which here constitutes the "at least one void", is shaped like a ribbon with a circular portion 50 and an outwardly extending portion 52. Furthermore, the radiating cut lines are omitted. The carrier of fig. 5 may be used in the lighting device 10 shown in fig. 2

Fig. 6 is a flow chart of a method of manufacturing a lighting device according to an embodiment of the present invention. The method will be described with reference to the carrier 12 of fig. 1 and the lighting device 10 of fig. 2, though it applies to other carriers and lighting devices as well.

In step SI, the carrier 12 is provided in a flat state. The carrier 12 may originally be a plate-shaped rectangular or square carrier, which subsequently is shaped with the curved outer perimeter 18 and the central through hole 20.

The light sources 28 are then mounted on surface 34 of the flat carrier 12 (step S2). The light sources 28 may for example be soldered to the carrier 12.

The flat carrier 12 is also structured by cutting the radiating lines 30, for example using a laser. The cutting can be made before or after the light sources are mounted.

Thereafter, in step S3, the shaped and structured carrier 12 is bent such that the surface 34 on which the light sources 28 are mounted form a double curved surface.

Step S3 may for example be performed by sandwiching the carrier(s) 12 (12') between the two pre-formed cover members 42a and 42b, whereby the carrier(s) 12 (12') folio w(s) the geometry of a double curved surface of the cover members 42a and 42b.

Alternatively, one carrier can be attached to each cover member using an adhesive, and then the two cover members 42a and 42b are assembled (i.e. closed). Also, the carrier(s) may be pre-bent before being arranged between the cover members 42a and 42b.

The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

For example, the through hole 20 may have a minimal size or it can be omitted (fig. 7a). Depending on the curved surface that one wants to realize, the "point" where the segments formed by the lines 30, 30' join can also be positioned offset from the very center of carrier 12 (fig. 7b). Furthermore, the segments formed by the lines 30, 30' do not have to join in one and the same point (fig. 7c). Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

Claims

CLAIMS:

1. A lighting device (10), comprising:

a carrier (12) including a substrate (14) and electrical connection means; and light sources (28) mounted on a surface (34) of the carrier and connected to the electrical connection means,

wherein the carrier is shaped with an outer curved perimeter (18) and structured by at least one void going through the substrate of the carrier, wherein the at least one void includes a line (30') which extends all the way to the outer perimeter, and wherein the carrier is bent such that said surface on which the light sources are mounted forms a double curved surface which resembles a double-helix.

2. A lighting device according to claim 1, wherein the carrier includes a central through-hole (20).

3. A lighting device according to claim 1 or 2, wherein the at least one void includes lines (30) radially extending from a central region of the carrier towards the outer perimeter of the carrier.

4. A lighting device according to claim 3, wherein said lines (30) do not extend all the way to the outer perimeter of the carrier.

5. A lighting device according to any preceding claim, wherein the electrical connection means include(s) an electrically conducting layer (16) provided over the substrate, and wherein electrically conducting layer includes electrically insulating separations (24).

6. A lighting device according to claim 3, wherein the light sources are positioned offset compared to said lines.

7. A lighting device according to claim 5 and 6, wherein the light sources are positioned on Z-shaped diversions (46) of the electrically insulating separations.

8. A lighting device according to claim 5 and 6, wherein the light sources are positioned on U-shaped diversions (48) of the electrically insulating separations.

9. A lighting device according to claim 3 and 5, wherein the lines are aligned with the electrically insulating separations.

10. A lighting device according to any preceding claim, wherein said carrier is a first carrier (12), wherein the lighting device further comprises a second carrier (12') with light sources mounted thereon, and wherein the first and the second carriers are arranged back to back with a heat resistant foam layer (54) in between.

11. A lighting device according to any preceding claim, further comprising:

a base (36) for connection to lamp socket;

a driver (40) electrically connected to the light sources; and

at least one optically transmissive cover member (42a;42b) covering the light sources.

12. A method of manufacturing a lighting device (10), which method comprises:

providing (SI) a flat carrier (12) including a substrate (14) and electrical connection means;

mounting (S2) light sources (28) on a surface (34) of the flat carrier, wherein the carrier is shaped with an outer curved perimeter (18) and structured by at least one void (30) going through the substrate of the carrier, wherein the at least one void includes a line (30') which extends all the way to the outer perimeter, and wherein the method further comprises:

twisting (S3) the shaped and structured carrier out of its original plane such that said surface on which the light sources are mounted forms a double curved surface.

13. A method according to claim 12, wherein bending the carrier includes sandwiching the carrier and optionally another carrier (12') between two 3D shaped cover members (42a, 42b) of the lighting device.

14. A method according to claim 12, wherein the carrier (12) is attached to a 3D shaped cover member (42a) of the lighting device, wherein another carrier (12') is attached to another 3D shaped cover member (42b) of the lighting device, and wherein the 3D shaped cover members then are assembled.

15. A lighting device according to claim 1, wherein the carrier is positioned in parallel to the longitudinal axis of the lighting device.

16. A lighting device according to claim 1, wherein the carrier is bent as illustrated in figure 2 of the drawings.